Our research program has continued to focus on assessing the possible role oxidative stress state (OSS) may have as a primary cause of aging and that longevity determinant mechanisms may include the numerous different strategies that control OSS. In these studies it is essential to employ sensitive and reliable assays to measure OSS in specific tissues, cells and in the whole organism using both invasive and non-invasive techniques. Towards this objective we have been continuing our development of our Oxygen Radical Absorption Capacity (ORAC) assay and of a PCR technique designed to measure the OSS history of a cell by determining the 8-OHdG per dG content of total DNA as related to 5KB deletions in mitochondria DNA. We have also continued our studies examining the hypothesis that some aspects of normal aging - particularly in spatial memory and motor control - may involve a deficiency in nitric oxide (NO). In these studies we have used the spin trap N-tert-Butyl alpha Phenylnitrone (PBN) plus several other spin traps which have now been found to release NO after reaction with a hydroxyl radical. We have discovered that PBN injected old rats show a remarkable recovery in sensitivity to induction of dopamine release in striatal tissue. PBN addition to the drinking water of 18 month old mice (0.25-1.0 mg/ml) appears to lengthen mean life span by about one month. Breath analysis of ethane and isoprene by GC to measure total body lipid peroxidation and cholesterol synthesis is now being evaluated as another useful assay of OSS.